JP2967601B2 - Coating method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION

FIELD OF THE INVENTION The present invention relates generally to shaft seals and, more particularly, to a method for forming a coating on a seal surface in a reactor coolant pump.

[0002]

2. Description of the Prior Art In a pressurized water nuclear power plant, a reactor cooling system is used to transfer heat from a reactor core to a steam generator for generating steam. The steam is used to drive a turbine generator. The reactor cooling system has a plurality of independent cooling loops, each cooling loop connected to the core and including a steam generator and a reactor coolant pump.

[0003] Reactor coolant pumps are generally hot and high pressure, eg, about 288 ° C (550 ° F), about 176 kg / cm ² (2500p).
This is a vertical single-stage centrifugal pump designed to move a large amount of reactor coolant in si). This pump is basically
From the bottom to the top, there are three universal parts: a hydraulic part, a shaft seal part and a motor part. The lower hydraulic section has an impeller mounted on the lower end of the pump shaft (hereinafter also referred to as the "pump shaft"), and the impeller is mounted within the pump housing to pump reactor coolant to the corresponding loop. Driven. The upper motor portion has a motor coupled to drive the pump shaft. The middle shaft seal part has 3 parts arranged in series.
It has two shaft seals or sealing devices: a lower first sealing device, an intermediate second sealing device and an upper third sealing device. These sealing devices are arranged near the upper end of the pump shaft and coaxially with the pump shaft. The purpose of cooperating them is to mechanically prevent high positive pressure coolant of the reactor cooling system from leaking into the reactor containment atmosphere through the pump shaft during normal operation. A typical example of a conventionally known pump shaft sealing device is disclosed in U.S. Pat.
Nos. 3,522,948, 3,529,838, 3,632,117, 3,720,222, 4,275,891, 4,690,612 and 4,693,481.

Historically, reactor coolant pump shaft seals
The (sealing device) is a major problem for the pump and has a considerable effect on the capacity factor of the nuclear power plant. The sealing device has a high system pressure (approximately 176 kg / cm ² (2
500psi)) must be safely controlled.
Three sealing devices of the series arrangement is used to suppress the pressure, in particular, the first sealing device bottom, absorbs most of the pressure drop (about ^{159kg / cm 2 (2250psi))} . The lower first sealing device is the main seal of the pump. This first sealing device is typically a hydrostatic membrane-supported leak control seal, the main components of which are an annular runner that rotates with the pump shaft and a non-rotating seal that remains stationary with the pump housing. It is a ring. Although the runner and seal ring of the first sealing device are not adapted to contact or slide with each other, the corresponding components of the intermediate and upper sealing devices, namely the rotating runner and the non-rotating seal ring, are in contact type. Or a sliding seal.

Conventionally, runners which are components of a contact-type sealing device (an intermediate second sealing device and an upper third sealing device) are made of stainless steel having a chromium carbide coating on a surface in contact with the seal. Of the substrate. Coating is explosion gun or detonation gun (de
It is formed by depositing chromium carbide powder on a stainless steel substrate using a tonation gun) technique. Bonding between the coating and the substrate is obtained solely by the mechanical impact force of the powdered chromium carbide impinging on the substrate. The density of the coating provided in this way is
It is generally well below 100% of theoretical density.

[0006] Chromium carbide coatings formed as described above have been found to be less than satisfactory. That is, it was observed that blistering occurred in the runner having the chromium carbide coating. Blistering is generated by contact with corrosive substances, such as chlorine-containing compounds and sulfur-containing compounds, that make up nuclear water chemistry applied in nuclear reactors. Such corrosive materials penetrate through the pores of the chromium carbide coating to the interface between the stainless steel substrate and the coating. The formation of hydrogen gas generated by this corrosion eventually causes peeling of the coating surface, that is, blistering. Thus, blistering is due to the porosity inherent in conventional coatings and the non-optimal bonding at the stainless steel / coating interface.

A recent measure for improving the coating of chromium carbide is disclosed in Japanese Patent Application Laid-Open No. 2-298276 . In that approach, the use of a detonation gun deposits the molten powder as a coating on a stainless steel substrate, then encapsulates the coating and further increases the coating to near maximum theoretical density. Hot isostatic pressing (HIP) to increase density
Is to be applied. In this hot isostatic pressing process, the coating is subjected to a high temperature, high pressure cycle to remove pores and sinter to allow metallurgical bonding between the components of the coating. However, to avoid the release of gas in the encapsulated coating, the maximum temperature reached during the hot isostatic pressing process is below the melting point of the constituent materials of the coating. .

This means employs detonation gun technology to deposit the coating on the substrate, even though it is suitable as a method for removing pores in the deposited coating and thereby reducing blistering. Thus, the quality of the bond obtained between the coating and the substrate is limited. The powder that forms the coating is a mixture of ceramic and metal binder, both of which, in order to be sprayed using detonation gun technology,
It must be in a molten state. The detonation gun deposits the molten mixture in a clay-like manner and cools rapidly as they adhere to the substrate. The cooled clay-like mixture is a sub-optimal interparticle bonding coating that forms a coating that is prone to microcracking and delamination in a thermal cycling environment.

The subsequent application of hot isostatic pressing to the deposited chromium carbide coating densifies the coating, but generally does not avoid the problems caused by the use of a detonation gun. is there.
Therefore, there is a need to improve the means to further improve the applied coating.

[0010]

SUMMARY OF THE INVENTION The present invention provides an improved method of forming a coating on a substrate to satisfy the above needs. Abrasion resistance provided by coatings by forming better interparticulate bonds between the composition of the coating, improving the bond between the coating and the substrate, and improving the densification of the coating , Corrosion or erosion resistance and thermal properties are improved.
The present invention eliminates the application of plasma spray deposition by detonation gun technology. In the present invention, instead of the detonation gun technique, the powder forming the coating is applied in a loose state or is applied in a partially hardened state as a preform. We have also introduced a powder treatment that can eliminate the use of detonation gun technology.

More specifically, the processing of the powder
The gas content of the powdery mixture can be reduced, the powder can be a mixture of ceramic particles at least partially thinly coated with a metal binder, and the melt spray by detonation gun technology can be used. It is possible to eliminate the need to adhere the powder in such a way,
During the process of hot isostatic pressing, the temperature of the adhered powder that forms the coating near the melting point of the components of the metal binder is increased, and the subsequent cooling of the coating and the substrate is controlled to join the particles. And the bonding between the coating and the substrate can be improved.

Accordingly, the present invention is directed to a method for forming a coating for forming a coating on a sealing surface of a component of a sealing device, such as used in a reactor coolant pump. This coating forming method comprises the steps of (a)
Treating a powder comprising the mixture so as to significantly reduce the gas content in the mixture of ceramic particles and metal binder and to at least partially coat the ceramic particles with the metal binder. (B) attaching the mixture of powders to grooves formed on the sealing surface of a component of the sealing device to form a coating on the sealing surface; and (c) forming at least the coating on the sealing surface. By attaching a metal cover to cover the coating,
At least encapsulating the coating, (d) evacuating the air between the cover and the coating on the sealing surface, and (e) compressing the coating to a substantially maximum theoretical density. Densifying, metallurgically bonding the coating to the sealing surface in the groove,
Forming a wetting of the ceramic particles with the metal binder;
And a step of hot isostatic pressing of the coating and the components encapsulated by the cover in a manner of bonding the fine particles between the ceramic particles wetted by the metal binder. Become.

Further, the coating forming method further comprises: (f) a step of cooling the coating encapsulated by the components of the sealing device and the cover at a predetermined rate; and (g) removing the cover from the coating after cooling. Removing step. The cooling is performed, for example, at a rate of about 100 ° C. per hour.

More specifically, the step of treating the powder comprises a sub-step of mixing the ceramic particles and the metal binder to form a mixture of the ceramic particles and the metal binder, and a step of mixing with the molten metal binder. Heating the mixture of ceramic particles and metal binder to a melting point of the metal binder lower than the melting point of the ceramic particles to form a group of coated and reduced gas content ceramic particles;
Sub-step of cooling the ceramic particles coated with the molten metal binder to form a solid mass thereof;
Grinding a mass of ceramic particles coated with a metal binder to granulate the powder mixture of ceramic particles to a desired size while remaining at least partially coated with the metal binder; and , Including. The step of applying the powder mixture comprises applying the powder mixture in a loose state or in a partially hardened state as a preform.

Furthermore, the step of hot isostatic pressing of the coating encapsulated by the components of the sealing device and the cover may be sufficient to cause wetting of the ceramic particles by the metal binder. It is performed at a high temperature below the melting point of the metal binder but close to that temperature. The high temperature in hot isostatic pressing is 200 ° C, the melting point of the metal binder.
It is preferably within the range.

The above and other features and advantages of the present invention will become apparent to those skilled in the art from a reading of the following detailed description, taken in conjunction with the drawings, illustrating embodiments of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following description, the same reference numerals indicate the same or corresponding parts throughout the drawings. Further, in the following description, words such as “front”, “rear”, “left”, “right”, “upper”, “lower” are words for convenience and are understood as limiting words. It should not be.

[0017]

Conventional Reactor Coolant Pump Referring to the drawings, and more particularly to FIG. 1, there is schematically shown one of a plurality of cooling loops 10 in a conventional general reactor cooling system. The cooling loop 10 includes a steam generator 12 and a reactor coolant pump 14 connected in series to a reactor core 16 in a closed circuit.
The steam generator 12 has an inlet plenum 20 and an outlet plenum 22.
And a primary system pipe 18 communicating with the primary system. An inlet plenum 20 of the steam generator 12 is communicatively connected to an outlet of the reactor core 16 and receives a high-temperature coolant from the outlet through a flow path 24 in a closed circuit. The outlet plenum 22 of the steam generator 12 is communicably connected to the inlet suction side of the reactor coolant pump 14 via a closed circuit flow path 26.
The outlet pressure side of the reactor coolant pump 14 is communicatively connected to the inlet of the reactor core 16, and supplies a low-temperature coolant to the inlet through a flow path 28 of a closed circuit.

Briefly, a reactor coolant pump
14 pumps coolant through a closed circuit at high pressure. For details,
The high-temperature coolant flowing out of the core 16 is guided to an inlet plenum 20 of the steam generator 12, and a primary pipe 18 communicating therewith.
Will be introduced. The high-temperature coolant flows in the primary system pipe 18 in a heat exchange relationship with cooling water supplied to the steam generator 12 via known means (not shown). Thus, the feedwater is heated and a portion is converted to steam used to drive a turbine generator (not shown). The coolant whose temperature has been lowered by the heat exchange is recirculated to the reactor core 16 via the reactor coolant pump 14.

The reactor coolant pump 14 must be able to pass large amounts of coolant at high temperatures and pressures throughout the closed circuit. Before the heat exchange, the temperature of the coolant flowing from the steam generator 12 to the pump 14
Although cooled significantly below the temperature of the coolant flowing to 12, it is still relatively high, typically about 288 ° C (550 ° F). The coolant pressure provided by pump 14 is typically about 176 kg / cm ² (2500 psi).

As shown in FIGS. 2 and 3, the conventional reactor coolant pump 14 generally has a seal housing 32 at one end.
A pump housing 30 terminating at the end. Further, the pump 14 has a pump shaft 34, and the pump shaft 34
It extends at the center of the pump housing 30 and is sealably and rotatably mounted within the seal housing 32. Although not shown, the lower part of the pump shaft 34 is connected to the impeller, and the upper part is connected to a high horsepower induction type electric motor. As the motor rotates the pump shaft 34, the impeller inside 36 of the pump housing 30 cools through the pump housing 30 at a pressure ranging from ambient pressure to a cover gas pressure of about 176 kg / cm ² (2500 psi). Circulate the material. Since the outer portion of the seal housing 32 is surrounded by the surrounding atmosphere, the pressurized coolant exerts an upward static load on the pump shaft 34.

The pump shaft 34 can rotate freely within the seal housing 32 while maintaining a pressure boundary of approximately 176 kg / cm ² (2500 psi) between the interior 36 of the pump housing 30 and the exterior of the seal housing 32. A lower first sealing device 38, an intermediate second sealing device 40, and an upper third sealing device 42, which are arranged in series, are arranged in the pump housing 30 around the pump shaft 34 in FIGS. It is provided at the position shown in FIG. First sealing device 38 of the lower responsible for most of the pressure sealing (approximately 158kg / cm ² (2250psi)) is a hydrostatic contactless, while the second and third sealing device 40, 42 contact・ Mechanical type by friction.

Generally, each sealing device 38 in the pump 14
40, 42 are annular runners 44, 46, 48 mounted for rotation integrally with the pump shaft 34, and a seal housing.
Each has an annular seal ring 50, 52, 54 fixed within 32. The paired runners 44, 46, 48 and the sealing rings 50, 52, 54 each have an upwardly facing surface 56, 58, 60 and a downwardly facing surface 62, 64, 66, respectively. ing. Runner 44 in lower first sealing device 38
The opposing surfaces 56, 62 of the seal ring 50 and the seal ring 50 do not usually contact each other, and a fluid film generally flows between them. On the other hand, the runner 46 of the intermediate second sealing device 40 and the seal ring 52
And the runner 48 of the upper third sealing device 42
The opposed surfaces 60, 66 of the seal ring 54 and the seal ring 54 are generally in contact or frictional engagement with each other.

Since the first sealing device 38 normally operates in a membrane-support mode, the cooling leaking into the annular space between the seal housing 32 and the pump shaft 34 rotatably mounted on the seal housing 32. Some action must be taken to dispose of the wood. Accordingly, the seal housing 32 has a first leak-off port 68, while the second and third leak-off ports 70,72 handle coolant leaking from the second and third sealing devices 40,42. .

[0024]

Next, FIGS. 4 and 5 show the annular runner 46 of the second sealing device 40 of the contact type. This runner 46 is, for example, 30
It is in the form of an annular substrate 74 made of 4,316 or 410 type stainless steel and having a central opening 76. Further, an annular groove 78 is formed in the upper contact seal surface 58 outside the base 74. For example, the depth and width of the groove 78 are respectively
It is 0.178 mm (0.007 in.) And about 12.7 mm (1/2 in.).

According to the coating forming method of the present invention,
A coating 80 (preferably a coating of one or more ceramic or refractory particles coated with one or more metal binders) is provided in an annular groove in the outer sealing surface 58.
It is attached so as to fill 78 and protrude outward from it. In the illustrated embodiment, the applied coating 80
Has a thickness in the range of about 0.152-0.203 mm (0.006-0.008 in.). A similar coating is also applied to the grooves of the runner 48 of the third contact device 42. Therefore, the coating forming method of the present invention is applied to both the runner 46 and the runner 48.

To improve the abrasion, corrosion or erosion resistance and thermal properties provided by the coating 80, the coating forming method of the present invention as shown in block diagram form in FIG. 6 is used. Block 82
FIG. 3 shows a first step of the present forming method, in which powder composed of a mixture of ceramic particles and a metal binder is treated. As will be described in detail below, this processing step pre-treats the powder, greatly reduces the gas content of the mixture, and at least partially coats the ceramic particles with a metal binder.

Block 84 illustrates the second step of the present forming method, in which the powder mixture is applied to the groove 78 of the sealing surface 58 to form a coating 80 on the sealing surface 58 of the base 74 of the runner 46. To adhere. This adhering step may be performed by adhering the powder mixture in a loose state, or by adhering the powder mixture in a partially solidified state as a preformed insert.

Block 85 of FIG. 6 illustrates the third step of the present method of encapsulating the coating 80 on the sealing surface 58. In either of the two embodiments, the coating 80
Can be used for encapsulation. As shown in FIG. 7, the base 74 of the runner 46 and the coating 74 are enclosed in a closed vessel 86 made of a suitable material such as stainless steel or molybdenum.
By sealing 80, both substrate 74 and coating 80 are encapsulated. Also, the inside of the container 86 and the upper surface of the runner 46
Between each of 58 and the lower surface 92, a ceramic insert,
That is, it is preferable that the powder 88 be disposed together with the molybdenum thin plate so that the runner 46 can be reliably separated from the container 86.
On the other hand, as shown in FIG.
It may be encapsulated by 94 and sealed from the outside atmosphere. The cover 94 is made of a suitable material such as stainless steel or molybdenum and has a
It is welded by an electron beam at 94A. FIG. 6 block
Reference numeral 96 denotes a fourth step of the present forming method. This fourth step comprises the steps of forming the container 86 or the cover 94 and the sealing surface 58
From the space between the upper coating 80 and the pipe 97 shown in FIG.
Is evacuated through a vacuum.

Block 98 represents the fifth step of the method, in which the coating 80 is densified to a substantially maximum theoretical density while the coating 80 is densified.
Container 86 or cover 94 for metallurgically bonding the sealing surface 58 of the base 74 within the groove 78 of the base 74 of the runner 46.
The runner 74 and the coating 80 encapsulated by the above are subjected to hot isostatic pressing. More specifically, the substrate 74 with the coating 80 is placed on a typical hot isostatic pressing machine (not shown) and subjected to a high pressure and high temperature cycle.
The material of the container 86 or cover 94 can withstand such high pressure and high temperature cycles. Hot isostatic pressing is
It is preferably carried out at a pressure in the range 351 to 2109 kg / cm ² (5000 to 30000 psi).

One of the improvements according to the invention is that the metal binder forms a so-called wetting of the ceramic particles, so that the inter-particulate bonding between the ceramic particles is less than the melting point of the metal binder, And performing the hot isostatic pressing of block 98 at a high temperature close to This temperature is preferably within 100 ° C. of the melting point of the metal binder. For example, if the metal binder is nickel chrome (Ni
Cr), the temperature is the melting point of nickel chromium,
It is within 200 ℃ of 1394 ℃.

The block 100 shown in FIG.
Runner substrate 7 with coating 80 encapsulated by 4
6 shows a sixth step of the present forming method for cooling the fourth step. Base 7
Cooling should be limited to about 100 ° C. per hour to mitigate problems associated with differences in the coefficient of thermal expansion of 4 and coating 80. In other words, cooling is about 100 ° C per hour
Done at the rate of

When the hot isostatic pressing and cooling steps are completed, the container 86 or cover 94 is removed, as indicated by block 102, which shows the seventh step of the present forming method in FIG. Thereafter, the base 74 and the coating 80 of the runner 46 are cleaned and finished.

Referring to FIG. 9, there is shown a flowchart of a sub-step constituting the first step (part indicated by the block 82 in the flowchart of FIG. 6) of the powder processing in the coating forming method of the present invention. The first sub-step of powder processing, indicated by block 104 in FIG. 9, is to mix and blend the ceramic particles and the metal binder to form the desired mixture of ceramic particles and metal binder in the desired proportions. This is the process. The amount of metal binder used is usually in the range of 15 to 40% by weight of the mixture, the minimum amount necessary to form good wetting of the ceramic particles in the hot isostatic pressing process described above. Should be. One example of a suitable mixture composition is CrC and NiCr. WC-Co-C for some applications
u or other ceramics such as Al ₂ O ₃ , Si ₃ N ₄ or Co or N
Other metal binders such as i can also be used. The choice of metal binder is based on its compatibility with the ceramic and its corrosive or abrasive properties for the particular application.

The second sub-step of the powder mixture process, shown at block 106 in FIG. 9, is to form a set of ceramic particles coated with a molten metal binder and having a reduced gas content. The mixture is pretreated by heating the mixture of ceramic particles and metal binder to a melting point of the metal binder lower than the melting point of the metal binder. This step ensures that the ceramic particles are usually surrounded by a layer of binder.

Block 108 of FIG. 9 illustrates a third sub-step of the powder mixture treatment of cooling the ceramic particles coated with the molten metal binder to form a solid mass; FIG. 14 shows a fourth sub-step of crushing a mass of ceramic particles coated with a binder and granulating a powder mixture of ceramic particles to a desired size. In this case, the granulated ceramic particles are still at least partially covered by the metal binder. In this state, the powder mixture is ready for the hot isostatic pressing process shown by the block 98 in FIG. At this time, the powder has a low gas content and, at the same time, has surface properties to form good wetting and fine particle bonding during the hot isostatic pressing process.

[0036]

Advantages of the coating forming method of the present invention From the above, the main advantages of the coating forming method shown by the flowchart of FIG. 6 are as follows.

(1) At the highest density, for example, CrC + NiC
A seal or coating of r is obtained, which removes gaseous pores that promote the corrosion mechanism and spalling.

(2) There is little or no oxidation of CrC + NiCr, so that the bonding between fine particles is improved, the tendency to cause delamination or spalling is reduced, and the thermal shock resistance is improved.

(3) The coating (coating 80) is in a state where stress is compressed and a state where cracking or delamination is not started.

(4) By controlling the pressure / temperature cycle of hot isostatic pressing, good interdiffusion is obtained at the boundary between the seal (coating) and the substrate, and the interface strength between the substrate and the coating is obtained. Is enhanced.

(5) The bonding strength between the fine particles of CrC—CrC is also
The corrosion resistance and the abrasion resistance are improved as compared with the conventional spray technology and powder metallurgy technology.

(6) Due to the presence of a good tight binder,
Resistance to thermal stress cracking is improved.

(7) A plurality of components can be formed (coated) in one cycle, thereby obtaining process consistency and making the process economically favorable in the long term.

(8) Depending on the vacuum state in the can (container),
The cladding and the cladding interface are gas-free and, as a result, the absence of species such as, for example, hydrogen greatly improves the corrosion resistance.

(9) The coating does not essentially crack and has high breaking strength.

(10) Multiple components can be processed during the same hot isostatic pressing cycle, ensuring process consistency and good economics.

The present invention and many of its attendant advantages include:
It will be understood from the above description. Further, various changes can be made in the form, configuration, and arrangement without departing from the spirit and scope of the present invention or without sacrificing the substantial advantages thereof. It should be clear that this is merely a preferred embodiment of the present invention.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing one of cooling loops in a conventional reactor cooling system including a steam generator and a reactor coolant pump connected in series with a reactor core of a reactor in a closed circuit.

FIG. 2 is a partially cutaway perspective view showing a shaft seal portion of a conventional reactor coolant pump, and shows a seal housing and first and second pump shafts disposed in the seal housing and surrounding the pump shaft; It is a figure showing the section with the 2nd and 3rd sealing device.

FIG. 3 is an enlarged sectional view of a seal housing and a sealing device of the conventional reactor coolant pump shown in FIG. 2;

4 is an enlarged longitudinal sectional view of a runner of a second sealing device in the reactor coolant pump of FIG. 3, showing a coating applied to a seal surface on an upper side of the runner.

FIG. 5 is a plan view of the runner as viewed along line 5-5 in FIG. 4;

FIG. 6 is a flowchart showing steps of a coating forming method of the present invention.

FIG. 7 is a longitudinal sectional view schematically showing an example of an apparatus for performing a hot isostatic compression molding step in the coating forming method of the present invention so as to cover the entire coating and the substrate.

FIG. 8 is a longitudinal sectional view schematically showing another apparatus for performing a hot isostatic pressing process in the coating forming method of the present invention so as to cover only the coating.

FIG. 9 is a flowchart showing sub-steps constituting a powder processing step in the coating forming method of the present invention.

[Explanation of symbols]

 14 Reactor coolant pump 30 Pump housing 32 Seal housing 34 Pump shaft 40 Second sealing device 42 Third sealing device 46, 48 Runner 58 Seal surface 74 Base 78 Groove 80 Coating 86 Container 94 Cover

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI F16J 15/34 F16J 15/34 F G21C 13/028 G21C 15/243 510G 15/243 510 13/02 F G21D 1/00 G21D 1 / 00 U (72) Inventor Eleanor Getriff, Meadowbrook Road, Marysville, PA 3591 (56) References JP-A-2-298276 (JP, A) JP-A-3-39993 (JP, B2) Japanese Patent Publication No. Sho 63-6630 (JP, B2) Japanese Patent Publication No. Sho 59-39055 (JP, B2) European Patent Application Publication No. 286024 (EP, A2) (58) Fields investigated (Int. Cl. ⁶ , DB name) ) G21D 1/04 GDP B30B 11/00 C04B 37/02 F01C 19/00 F04D 29/10 F16J 15/34 G21C 13/028 G21C 15/243 510 G21D 1/00

Claims (1)

(57) [Claims] 1. A coating forming method for forming a coating on a sealing surface of a component of a sealing device, comprising: (a) reducing the gas content in a mixture of ceramic particles and a metal binder; Treating the powder of the mixture so as to at least partially coat the ceramic particles with the metal binder; and (b) coating the sealing surface of the component of the sealing device. Adhering the mixture of powders into grooves formed in the sealing surface to form (c) attaching a metal cover so as to cover at least the coating on the sealing surface, Enclosing the coating; (d) depressurizing and exhausting air between the cover and the coating on the sealing surface; Densifying the coating to a substantially maximum theoretical density, metallurgically bonding the coating to the sealing surface in the groove, forming a wetting of the ceramic particles with the metal binder, and forming the metal bond. A step of hot isostatic pressing of the coating and the components encapsulated by the cover in such a manner that the ceramic particles wetted by the agent are bonded between the fine particles.